Vehicles typically include doors. The doors can be opened to allow occupants to enter and exit the vehicle. When closed, the doors, perhaps in conjunction with seatbelts, airbags, etc., can prevent occupants from exiting the vehicle in an impact. During an impact, the momentum of the vehicle may suddenly change relative to the momentum of the occupants; the doors may prevent the momentum of the occupants from carrying the occupants out of the vehicle by blocking a path for the occupants to move. Moreover, for vehicles with side curtain airbags, the doors provide a reaction surface for the airbags.